A great deal of research work has been conducted with the view of furnishing elastomeric polymers for various aerospace seal and sealant applications. In order for a polymer to fulfill completely the rigid requirements of such applications, it must be thermooxidatively and hydrolytically stable while having the capability of retaining its elastomeric properties at sub-zero temperatures. Previously, it has been possible to prepare polymers possessing two of these properties while one of the properties is less satisfactory than desired. Thus, in U.S. Pat. Nos. 3,846,376 and 3,994,861 polymers are disclosed by me that possess a broad use temperature range. However, the polymers are often hydrolytically unstable when exposed to humid conditions at elevated temperatures for extended periods of time. In my copending U.S. application Ser. No. 710,088, filed on July 30, 1976, and now issued as U.S. Pat. No. 4,064,109 polymers are disclosed that advance the art in meeting all three of the above-mentioned requirements. Thus, the polymers are thermally and hydrolytically stable and have a fairly low glass transition temperature (Tg). Since the Tg of a polymer is an indication of the temperature at which it retains its viscoelastic properties, there is still a need for thermally and hydrolytically stable polymers having even lower glass transition temperatures.
It is a principal object of this invention, therefore, to provide thermooxidatively and hydrolytically stable perfluoroalkylene ether bibenzoxazole polymers having improved low temperature viscoelastic properties.
Another object of the invention is to provide a method for synthesizing the polymers.
Other objects and advantages of the invention will become apparent to those skilled in the art upon consideration of the ensuing disclosure.